This RainBrain smart shower controller from Hansgrohe seems like one of those things that you didn't think you needed, but once you try it you can never go back to what you had before.

This thing controls music streamed wirelessly via Bluetooth, lighting in your shower and even (who'd have imagined) what kind of water is raining down on you. It even has a Scottish Shower mode, which I had to look up to find out that it meant alternating hot and cold water spray. [Hansgrohe via Trendir via DVice]